This invention relates to spas or hot tubs and, more particularly, to a pump allowing large volumes of water to have directional changes close to the pump impeller, the pump providing water under pressure to the spa jets.
The use of pumps in spas or hot tubs is, of course, known. Such pumps are used to take water from a water inlet, put the water under pressure and convey the water under such pressure to the various outlets or jets within the tub where the user is positioned. The water under pressure creates a flow within the tub and otherwise discharges on the user where it has a pleasant and therapeutic benefit.
The pumps that create the pressure, however, are typically centripetal type pumps. These pumps have an impeller with a central portion into which water from the water inlet is introduced. The impeller has a series of radially located vanes that convey the water from the central inlet area and exhaust it radially to an outlet located adjacent the radial vanes. While the centripetal type pumps are pervasive in the industry, they have disadvantages.
A first disadvantage is that the water volume supplied under pressure by the centripetal type pump is limited. This dictates the size of jets that can be used in order to impinge properly upon a user and create the currents within the tub. Second, with the use of a centripetal type pump, the operation is typically at the upper end of the volume capabilities of he pump. This causes unnecessarily high pump noise which is diversionary to the enjoyment of a spa user. Thirdly, since the volume of water being pumped is limited, the jets may be somewhat slower in acting than would otherwise be desirable.
U.S. Pat. No. 5,647,736 (French) teaches a motor cooling technique typically used in present spas. French takes ambient air from within a component compartment of a spa and passes such air through the motor which powers the spa pump by the use of the usual cooling fan within the motor. French teaches collecting the hot air which has passed through the motor by an exhaust shroud and exhausting such air to ambient conditions outside the component compartment of the spa.
While, again, the French technique operates generally in a satisfactory manner, advantages in such a cooling technique and increased flexibility with the cooling air is possible. First, because French takes his cooling air from within the component compartment, the location of electrical and electronic components within the compartment necessarily generates heat and, accordingly, the air gathered from the component compartment is at an elevated temperature which limits the cooling of the motor otherwise obtainable with air at a lower temperature.
Second, by exhausting his collected and heated air to a location outside the spa, the thermal energy of the heated air is wasted. The thermal energy, particularly in a spa, could be harnessed for other uses.
Thirdly, French does not cool the pump which is driven by the motor. His air is introduced into the cooling air inlet of the motor and does not reduce the temperature of the pump. Cooling the pump would assist is more efficient operation of both the pump and the motor.
Fourthly, centripetal type pumps typically do not have wide operating environment capabilities. They are prone to overheating if used in adverse conditions such as high altitude, low humidity, high ambient temperature conditions. Likewise, if the ventilation surrounding the pump is poor under the skirt of the spa for example, this also contributes to such problems.
According to one aspect of the invention, there is provided a spa having water jets used to discharge water which impinges upon a user, said spa comprising a pump having a pump water inlet with a pump water inlet axis, a pump water outlet operably connected to said water inlet and allowing water under pressure to pass from said pump water inlet to said pump water outlet, an axially rotating impeller and a relatively large plenum chamber located outside said impeller and having a plenum chamber outlet operably connected to said pump water outlet, said impeller propelling water outwardly of said impeller into said plenum chamber with a principal direction of movement of said water being radially outwardly from said pump water inlet axis to said plenum chamber, said plenum chamber being defined by a passageway having a generally concave inner and curved rearward surface and a variable cross sectional area, said cross-sectional area increasing as said water from said impeller moves around and within said plenum chamber from a position nearer said pump water inlet to a position further from said pump water inlet and closer to said plenum chamber outlet, said plenum chamber outlet being located at a radial position furthermost from said water inlet and allowing said water to move from said plenum chamber outlet to said pump water outlet, and thence to said water jets.
According to a further aspect of the invention, there is provided a method of providing water to the jets of a spa comprising introducing water along an axis to a pump water inlet of a pump, using an impeller to propel said introduced water from said pump water inlet in a generally radial direction to a plenum chamber surrounding said impeller while simultaneously providing said water with a velocity component within said plenum chamber from said pump water inlet to a plenum water outlet while the cross-sectional area of said plenum chamber increases from said pump water inlet to said plenum water outlet and smoothly transitioning said water from said plenum water outlet to a pump water outlet by the use of a smooth curved surface between said plenum water outlet and said pump water outlet.